For six years, New York City and state officials have tried to open a community court in Brownsville to straighten out kids who have done stupid things before they get into worse trouble. A similar court in Red Hook, Brooklyn, has been a blazing success. It reduced recidivism among young people by 20 percent while curbing incarceration, a saving of real money and future misery. The Red Hook court has been the model for more than 50 other community courts in the United States and around the world.

Just not elsewhere in Brooklyn.

“It boggles the imagination,” said Jonathan Lippman, who retired last month as the state’s chief judge and fought for the Brownsville court year after year. “There are some public policy matters where there is a reasonable debate. This is not one of them. There is no conceivable argument that I think can be made to not put this revolutionary concept, proven without a doubt, into place.”

It’s not just judges who think this is an excellent idea. The mayor supports it. The borough president. The city planning commission. The community board. The Brooklyn district attorney and the public defender organizations. A city-owned building at 444 Thomas Boyland Street in Brownsville has been selected as the site, and $23.5 million was set aside in the city’s capital budget two years ago for renovations.

Still, it has not happened.

One person stands in the way: Councilwoman Darlene Mealy, who effectively has a veto over the site of the proposed courthouse. After all of the city’s land-use procedures, the last stop is the City Council.

And there, by custom but not by law, the councilwoman for the district gets to decide if a project lives or dies. She has stopped it since it surfaced in the Council more than a year ago. “I’m still against it,” Ms. Mealy said Tuesday evening. “Every child in Brownsville is not going to jail.”

She suggests that a developer could build a court on sites that were not already crowded, as the area around Boyland Street is, with a police precinct, a detention center and a probation office. At her urging, she said, a development company, L&M, met with city officials about building near train stations. “The developer said they would do a boxing gym across the street for our young people,” Ms. Mealy said.

Red Hook two decades ago was ridden with violence. Among many changes is its community court, where defense lawyers, prosecutors and judges try to funnel people in smaller troubles toward a buffet table of alternatives to jail. There are plenty of well-intentioned programs that don’t work out. The Red Hook court is not one of them. A rigorous study conducted for the Center for Court Innovation compared cases in the regular criminal justice system with those that went through the community court. It found that people in the regular court were 15 times as likely to go to jail, that adults were 10 percent more likely to be arrested again within two years, and juveniles, 20 percent. The community court saved society $2 for every $1 spent.

Its advantages were so clear that the creation of a twin court in Brownsville had near unanimous support, Ms. Mealy aside.

“It is so ridiculous that this is still hanging out there,” Mr. Lippman said.

The Red Hook judge, Alex Calabrese, said the courts succeeded by solving problems, rather than shoving them down the line in the system. There are social services right in the court building. “The court backs up the services with power,” Judge Calabrese said.

As it happens, Judge Calabrese is in Israel this week along with officials from the Center for Court Innovation, who have supported community court developments in, among other places, Australia, Canada and South Africa.

“Israel has two community courts,” he said. “Brooklyn, just one.”

No one claims community courts head off all terrible crimes. “Shouldn’t we at least be trying?” Judge Calabrese said.